Cystopteris dickieana R. Sim is a fern species that currently receives legal protection in Britain on the basis that it is endemic to Scotland and extremely rare. However, ever since it was first discovered in the 1830s, there has been considerable debate about its taxonomic status within the Cystopteris fragilis complex. This debate centres on the relative importance of two characters, the architecture of the fronds and the surface sculpturing of the spores, in delimiting C. dickieana from other taxa in the C. fragilis complex and is complicated by the fact that most comparative studies reputed to have included ‘C. dickieana’ have failed to include either the type material of C. dickieana or material from the ’type population‘ (i.e. the population of plants, of uniform and distinctive morphology, that still grows at the type locality for C. dickieana). The principal aim of this investigation was to generate some of the critical data and information currently missing from the debate concerning the taxonomic status of C. dickieana by including material from the ’type population‘ in an allozyme study of several Scottish Cystopteris populations. The frond architecture, spore sculpturing, and allozyme banding patterns were investigated in five natural and two cultivated populations of the C. fragilis complex. All plants from the ‘type population’ of C. dickieana had the distinctive frond architecture and rugose spores of the type material. Two populations comprised plants that had the frond architecture and echinate spores typical of C. fragilis. Also examined were two populations containing plants that had frond architecture typical of C. fragilis but rugose spores similar to those of the type material of C. dickieana. These plants occurred with typical C. fragilis in one of the populations and with typical C. dickieana in the other. In the latter population, situated close to the ‘type population’ for C. dickieana, a third, ‘smooth’ spore type occurred in nine out of 55 fertile plants. Consistent and analysable allozyme results were obtained for seven enzymes at ten loci: eight loci were polymorphic and all but the smallest population showed variation at one or more loci. In total, 22 allozyme phenotypes were recorded in 226 individuals. No consistent correlation was found between frond architecture, spore sculpturing and allozyme banding pattern. Our results provide no support for the recognition of C. dickieana as a distinct species related to C. fragilis.

Colonization of mycorrhizal fungi was studied in a Pinus muricata forest on the coast in California, USA, burned by a stand-replacing wildfire in October 1995. Naturally established field seedlings of P. muricata were harvested 1 yr after the fire. The species composition of the mycorrhizal fungi on these field seedlings was dominated by Rhizopogon species, Wilcoxina mikolae and Tomentella sublilacina. Bioassays, set up with soil collected immediately after the fire, were used to determine which mycorrhizal species had colonized the burned area from resistant propagules. The P. muricata seedlings in these bioassays were dominated by suilloid and ascomycetous fungi, the same fungi which dominated the mycorrhizal flora of seedlings in pre-fire bioassays derived from the same forest site, suggesting that resistant propagules were the primary inoculum source for naturally establishing seedlings. Drying of post-fire soil for 1 month raised the number of bioassay seedlings associated with Rhizopogon olivaceotinctus, while the number of bioassay seedlings associated with Rhizopogon ochraceorubens was reduced. Fire appeared to have either stimulated or provided a competitive advantage to R. olivaceotinctus, which increased in abundance on the post-fire bioassay and field seedlings. Soil collected from the burned area was diluted with sterile soil in three different concentrations, and the number and frequency of mycorrhizal taxa on bioassay seedlings decreased with increased dilution. Although precise quantification was not possible, propagules of the Rhizopogon species were much more abundant than those of Tomentella or Wilcoxina species. Differences between the mycorrhizal associates of bioassay seedlings, naturally regenerated seedlings, and different inoculum sources are discussed.